A oobjpobation ox  bhode island



Reissued Feb. 1, 1928.

A CORPORATION 01 OD! mm.

This invention relates to processes for treatin water emulsions of rubber, that 1s rubber atex or similar material either in its original state or diluted; and to. the prod- 6 note so reduced. v

An ject of the invention is to provide a process wherein the fluid portion of the latex may be removed to produce a latex of h gher Anotherobject is to rovide a method for concentrating rubber atex.

The invention accordingly consists in segregating or collecting the'rubber containing 15 portion of a latex b withdrawmg the aqueous portion thereo from the latex preferabl without the use of heat.

is ap lication is a division of application for reissue No. 85,602, filed February 2,

It has been found that the deposit of rubber made by the immersion of porous materials in latex serves as a convenient means for concentrating the latex and obtaining a substance which may be reconvert'ed into the In other words the deposit on the surface of the porous material i placed in water will return to latex. Pressure of the particles or so agitation in forming the deposit on the form rior to their immersion in the water should avoided as such action tends to cause the deposit to form a mass which upon addition of water may be partially or wholly incaas 'pable of being converted into latex. The material removed from the porous surface contains normally 80-85% of rubber.

It has been found that the rate of deposition of the rubber on'the porous material 40 varies with the time of immersion, and the thicknessof the deposit lessens for succesnature of the absorbent medium. Substantially any porous material capable of sucking up water by capillarity appears to be able to deposit latex on its surface, and to rmit its removal therefrom. Of course it should not be porous to an extent such that the latex as a whole may pass through it. Surfaces which are satisfactorily absorb- UNITED STATES emsr 10mm, or new You, a. omens, or mm: nxcx, m

roux, assronoas 'ro Bevan mam serum, or oneness, uaseacxusl'r'rs,

. rubber concentration and containing a, 10 lower percentage of non-rubber constituents.

'terial known as silocel may be employed for original latex by simple additionof water.

sive equal intervals of time regardless of the atlas-14 PAT-Eur OFFICE. I

memes roe. rm'rmo ware-a numerous or amen. are rumours ms raomrcnn. 4

Io Drawing. Division 'of original Io; 1,548,, dated Juan, 1035, Serial Io. 588,116, fled Iebrury 8, 1m. Application for release fled retinal-7.11, 1986. Serial Io. 87,07.

Division B.

out but not suflicieiiily smooth can be made smooth by polishing or immersing them in a suspension of finely powdered china clay or similar porous material in finely wdered form with a subsequent drying oi izhe ch na clay or other coating on the form. Insteadof this dip ing, the clay or other material maybe ru bed or brushed on to the porous material. In place of the ung'lazed porcelain or china mentioned above the memaking the desired porous materials. This is a natural deposit of tightly comp, diatomaceous earth. Many of the water soluble constituents of the latex are withdrawn in solution from the latex into the interior of the porous material employed so that the deposit of rubber on the surface is lower in protein and salt content than would be obtained if the latex were evaporated down with all these constituents; The soluble constituents drawn into the porousmaterial may be washed out by immersion of the rous material in fresh water or by any 0 er desired means such as by heating or chemicals. Where substances are admixed it is preferred to keep the latex with the added material in agitation. This may be satisfactorily accomplished in the case of articles formed on the interior of a porous material as above 4 described by rotation of the porous material. According to the above described process. it is therefore possible to prepare a concentrated uncoagulated dis rsion of rubber which may contain as big as -85% of rubber and due to the fact that the porous inaterial rmits the exit of the aqueous portion 0 the latex, this concentrated latex will contain an appreciably lesser amount of nonrubber soluble materials such as soluble nitrogenous matter, inorganic salts, etc. than will be found in an untreated latex.

It is apparent that the above invention may be utilized to prepare a purified latex having arubber concentration which may be as high as 80-85%. It is likewise apparent from these facts that the process of the invention may be employed to bring latices containing varying amounts of rubber and of non-rubber soluble materials to a more or files uniform standard of rubber content and containing a considerably decreased percenta e .of the soluble non-rubber constituents w ich have lon been recognized as the prime causes of varia ility in rubber. The product of this invention may therefore be described as purified, concentrated and standardized.

a The latex employed in carrying out the. process is preferably that WhlCh has been reserved by addition of ammonia, formaliehyde, or other stabilizer or preservative, but if desired a latex free from such materials may also be employed containing 20-35% rubber.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. A process for concentrating latex which comprises continuously withdrawing moisture from within a body of latex without elevating its temperature and segregating, the uncoagulated concentrated latex in said body and recovering anuncoagulated product.

2. A process for concentrating latex which comprises withdrawing moisture therefrom by porous material, collecting the concentrated latex on the surface of said material and recovering the uncoagulated product.v

-3. A process for concentrating latex which comprises bringing latex in, contact with a porous structure impermeable to latex as a whole but permeable-to the water and dissolved constituents therein, depositing a coating on the structure having an uncoagulated rubber content higher than that of the original latex, and removing thereimm the uncoa ated product.

4. process for concentrating latex which comprises bringing latex'in contact with a porous structure impermeable to latex as a whole but permeable to the water and dissolved constituents therein. depositing a coating on the structure having a rubber content of to and removing therefrom an uncoagulated product. '5. As a new product a concentrated substantially uncoagulated water emulsion of Heoea braz'iliensis rubber particles containmg less non-rubber constituents than natural latex, said concentrated emulsion being capable of standing without separation of its aqueous portion. 1

anew product a concentrated sub-- stantially uncoagulated He'vea brazflieneis rubber latex containing a sub-normal amount of water-soluble non-rubber constituents. said concentrated latex being capable of standing without separation of its aqueous portion.

7. As a new product a concentrated substantial] uncoagulated He'vea braza'liemis rubber atex containing a preservative and having a sub-normal amount of non-rubber constituents, said concentrated latex bein capable of standing without separation o its aqueous portion.

8. As a new composition of matter, a rubber emul sion representing a concentrated, purified and-standardized Heoea brasi'le'emis atex, said emulsion being of thick consistm and being alkaline in reaction, said 9 concentrated latex being capable of standing without separation of its aqueous portion. 9. As a new composition of matter, a rubber emulsion representin a concentrated, unfied and standardized %e'vea atex, said emulsion being of thick consistency, being alkaline in reaction and the aque' ous hase containing less proportions of solub enon-caoutchouc solids than those nortrial to latex, said concentrated latex being capable of standing'without separation of its aqueous portion.

Signed at New York, New York, this 4th day of February 1926. EimEs'r HOPKINSON.

WILLIS a GIBBONS. 

